2.
Be very careful as a newbie with your mouse-clicks when the cursor is on the map. During my career i´ve lost hundreds of teams to bad-clicking. After playing a while you´ll get the hang of it. Click on the unit and click on the hex where you wan´t it to go. Avoid accidental clicks. Mean your click!
3. Browsing the encyclopedia for a single unit can be a challenge. I find it so fun, that in the heat of battle, I can start comparing totally different units and even nations in the encyclopedia. It is HUGE and getting bigger and better all the time. In the Mobhack you can search a given unit or weapon system typing it´s name on the search bar. Can be done when using windowed, not when using full screen version. (I´m not sure about this one though)
AI isn´t creative, but can handle it´s fights. Watch out for it, it is getting better and can deliver serious surprises. If in need of real challenge try the scripted campaigns. AI has waypoints etc. features scripted by humans that make it a lot more challenging. Check out the strategy/tactics posts in this forum to learn to fight.